J24 Quicktune Guide 2007

Mainsail Trim

Let’s break trim down into light, medium and heavy air, and look at some of the dynamics.

Light Air (0-7 Knots)

In light air the main is set with the traveler to weather to keep the boom on or just above center line. For the best combination of speed and pointing the top batten is parallel with the boom. The outhaul is eased 2” from the black band to power up the bottom sections and round up the lower leech. The top telltale on the leech will be streaming 80% of the time. This setup is for straight line speed. In a point mode, the boom will be pulled up some 3” to weather of centerline, and the mainsheet will be sheeted harder until the top batten is closed by as much as 6 degrees (sight up the middle of the sail using the boom as a guide for the top batten). The top telltale will be stalled about 50% of the time and the boat will point higher but go slower. To build speed out of tacks, through waves, or if the boat is slow for whatever reason, ease mainsheet so that the top batten is parallel and drop traveler till boom is on the centerline. Ultimately, traffic, tactical considerations, and moment to moment assessment of boatspeed relative to the competition will dictate your set up with regard to the relationship traveler and sheet tension. When in doubt err on the side of speed, and keep the leech of mainsail open.




Medium Air (8-14 Knots)

This is serious power-up pointing mode, especially at the bottom end of the range. At the bottom end of this range the outhaul is set 1” from the black band. The crew is fully hiked. What we are looking for is maximum load on the keel to create lift. Sheet tension is the secret. In 8-11 knots, we sail with the top batten hooked 5 degrees for straight line and 7 degrees for point mode. The difference in tension is 2 clicks on the ratchet block. At 10-14 knots we begin to de-power. The outhaul is maxed to the black band, and a combination of backstay, traveler, and mainsheet is used to flatten the sail and keep the boat on it’s feet The first adjustment is traveler down. Boom position will vary from centerline to leeward of center. If this is not enough the next adjustment is backstay. As backstay comes on the mainsail is flattened and the leech is twisted open. This will de-power the boat, but will also twist the leech. The more open leech will create pointing problems. Add mainsheet whenever backstay is added. One click in on the mainsheet will keep the boat pointing.

Heavy Air (15+ Knots)

Hike Hard! The outhaul is max, the backstay is on hard. The traveler is close to being all the way down, and chances are the main is flogging. In this range switch from traveler sheeting to vang sheeting, particularly if it is puffy. The new 8:1 purchase on the vang makes it easy to get all the vang tension that is necessary. The traveler is positioned three quarters of the way down, and the sheet is played for balance.

Genoa Trim

This sail must cover a very wide range (0-18 knots). Also, when in doubt about sail selection, we usually choose the genoa. As a result, it requires some creative and relatively extreme condtions of halyard, lead position, and sheet tension.

Light Air (0-7 Knots)

The halyard is kept very loose, with large three quarter inch scallops between hanks. The lead is set one or two holes forward of the 8 knot median settings.* The sheet is played constantly. In this range, the helmsperson will have to steer too much to keep up with changes in velocity and direction if no change is made to the sheet. Steer straight and make changes very gradual; keep the telltales flying by adjusting the sheet. Try to work back to the median (4-6” off the spreader setting) for this condition. A constant dialogue between trimmer and driver is helpful. The trimmer tells the driver how far off the leech is, and driver describes if he is working up or down, and whether or not the sail can be sheeted harder or it needs to stay eased to build speed.

Medium Air (8-14 KNOTS)

Luff tightened gradually (halyard or cunningham) so that just a hint of scallops are showing. Lead position moves aft to medianor as much as two holes aft of median. Sheet tension changes little in this range. Trimmer hikes and trim changes only for big sets of waves (ease sheet), or in a tactical situation (trimming harder to point, or easing to foot).

Heavy Air (15+ Knots)

Luff tension up tight to smooth all wrinkles. Lead back between three and seven holes. The sheet and lead position are set largely as a function of boat balance. Trim the genoa relative to how the mainsail is being setup to keep the boat upright. If the mainsail is flogging constantly, move the lead back. If this is not enough, ease the sheet slightly so that both sails are luffing evenly. In the light spots, the sail can be trimmed harder, and/or the lead moved forward. In flat water you can usually sheet harder and de-power with the lead aft. In choppy water, it is important to ease the sheet.

*A Note On Lead Position: Drill genoa tracks out so that there are two holes between every factory hole. Median lead position is determined in 8 knots of breeze. In this condition, trim the genoa so that it touches the tip of the spreader and the chain plate at the same time. From here maximum forward will be two holes and maximum aft will be seven holes Moving the lead aft increases the distance of the leech off the spreaders, and brings the foot in on the chainplates. (See sail trim chart for distances off of spreader and chain plate).

Jib Trim

We designed the blade to overlap the genoa. This enables lighter teams to compete with heavier teams at the upper end of the genoa’s range. The blade’s range is 17+ knots. Halyard/cunningham tension is always set to keep the luff smooth. (To get maximum tension, sail the boat downwind with the backstay completely off. With two people, pull as hard asyou can.) The median lead position is set by placing the plunger of the jib lead directly perpendicular to the lower shroud. This is the position that you will use about 80% of the time. With the lead at median, mark the jib sheet at a point just in front of the block, so that when the sail is trimmed to this mark the middle batten is parallel with the centerline of the boat, and the upper leech is about 3” inside the spreader tip. This provides a point of reference. The leech of the sail will be trimmed from a point 3” inside the spreader tip to as much as 3” outside the spreader tip as the breeze builds. In more than 24 knots, slide the lead back one inch to de-power. If you get caught in a situation where the boat is overpowered and you cannot adjust the lead, (or it is already back), ease the sheet an inch or two, (or whatever it takes to balance the boat). This will quickly de-power the head of the sail and the boat will drive off the bottom of the sail.

Spinnaker Trim

Standard rules of spinnaker trim apply, though because of the rule’s effect on sail geometry, and because the sail design is geared more towards windward/leeward courses, reaching trim requires some exaggeration of normal technique. A couple of thoughts to keep in mind:

In 0-14 knots sail with the pole on the lower ring. In 14+ knots use the upper ring. In windier conditions, if you are tight reaching, the outboard end of the pole should be a foot lower than perpendicular to the mast. This will slide the draft forward in the sail and open up the leech to de-power the boat. Keep the pole 3-6” off the headstay. When broad reaching and running in all conditions, the tack should be slightly lower than the clew. This, coupled with the pole being squared, will help project maximum sail area. When broad reaching and running, always work to square the pole as far back as possible. Ease the sheet to maintain a curl, but make sure the bottom of the sail is underneath the top. The luff should run straight from tack to the point of curl. If the head can be eased to weather of the straight line, the pole is undersquared.